Protein, cell, and bacterial fouling of surfaces occur spontaneously upon exposure of medical implants and diagnostic devices to physiologic fluids and tissues. In many cases biofouling is an adverse event that can impair function or even cause catastrophic failure of medical devices. Examples of problematic biofouling include occlusion of cardiovascular implants by thrombus, protein accumulation onto biosensor surfaces, and bacterial colonization of indwelling catheters. Complications arising from fouling of medical implants and devices significantly increase the cost of healthcare delivery and can lead to reduction of implant performance, implant failure, and patient infections.
Strategies in the art for inhibiting biofouling are directed to grafting antifouling polymers or self-assembled monolayers (SAMs) onto surface. Technical issues critical to the longevity and antifouling performance of such organic coatings include the nature of the chemical bond used for anchoring such coatings onto surfaces, as well as the chemical characteristics of the polymer/SAM. Common anchoring chemistries include thiol- and silane-containing molecules on metals and metal oxides, respectively, electrostatic interactions between polyelectrolytes and charged surfaces, and numerous strategies that take advantage of reactive organic functional groups on surfaces and molecules in solution or the vapor phase. While oligoethylene glycol terminated SAMs have shown excellent antifouling properties, their stability under in-vivo conditions may be limited in certain applications. A variety of polymers have been investigated as antifouling coatings, including poly(ethylene glycol) (PEG), poly(methoxyethyl acrylate) (PMEA), poly(phosphorylcholine methacrylate), and glycomimetic polymers. Each of these polymers has met with some success in in-vitro and in-vivo antifouling tests. However, none have yet proven to be ideal for long-term prevention of protein, cell, and bacterial fouling of surfaces.